180 degree sail arm servos

Does anyone have any experience at all with the servo stretcher for sail by Servo City. It is supposed to allow the servo to be adjusted readily to any angle of arm turn.

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I have one in the toolbox but have never used it. Just pulled it out to try since the radio I want to use in my current project does not have endpoint adjust - DX5e. It weighs 15 grams. I hope to install and try it over the weekend. will let you know how it works.


Thank you for your reply. I’d also like to know the source too.

To NateG:
Did you get a chance to try out the Servo Stretcher on the weekend?
My reason for my interest is that I bought (about 2 years ago) an HS-755HB Hitec servo, with the intention of adding two 1Kohm resistors at the ends of the potentiometer, just as I had done previously with a HS-715BB Hitec servo to use as the 180 deg sail arm servo in my Soling 1M. However, when I finally opened the case, I found that the design had changed and that taking it apart required un-soldering the motor connections from the circuit board. When I went back to the model store, they said that the HS-715BB was obsolete, and I was sort of out of luck. I emailed Hitec, but they replied that my only solution was to do the unsoldering (which I was reluctant to risk). I then heard about the servo stretcher, and made my inquiry to the Forum. The servo is intended for my 1 metre Chinese chu’an (“junk”) which I had been sailing with a home-made sail winch, controlled by a standard servo through a pair of micro-switches and a ‘follower’ arm. This was proving too complicated and unreliable.

Rod -

the Servo-Stretcher is sold by Servo-City and allows end point adjustments of servo movement that can be different on each side/end of the arm movement. Runs about $20 (US)


They also sell selected servos already modified internally to provide 180 (or continuous) rotation. I purchased some HS-645MG servos for RG-65 boats, but found they only moved about 90 degrees or less. I sent them in and for $10 the company sent me pre-modified ones that swing 180 degree on exchange. My servos were still a current model and unused.

You can also purchase other Hitec servos for reasonable costs and at time of order, add $10 for 180 degree turn, or $20 for continuous rotation. My electronic knowledge and skills being what they are have prompted me to recommend to others to spend the additional $10 for 180 degree travel.

If I recall correctly, those model 645 servos ran around $38 so my final selection cost me $48 - meanwhile buying a Servo Stretcher would have cost me $58 with the only benefit being different end point adjustments which I didn’t require.

Here is link to their web page. http://www.servocity.com/html/180o_servo_stretcher.html

I have had excellent response to technical questions from their staff, as well as fast deliveries.

Regards, Dick

I have used the “Servo-stretcher”, but only in big boats like the Soling 1m where the boat is way under the weight limit.
My last three Footys have used the HS-225BB servos modified for 180 degree travel by Servo City. They are probably overkill, but they are plenty powerful and fast and I play the sail control almost constantly.